1. Field of the Invention
This invention relates to an ink termination detecting device for detecting ink termination in the ink storing container or the like of an ink jet recording apparatus for discharging ink to thereby effect recording, or a remain state detecting device for detecting the remain state of ink. Particularly, this invention relates to an ink remain state detecting device for and a method of detecting the remain state of ink contained in an ink storing container comprising a plurality of containing members capable of containing ink which communicate in different states.
2. Related Background Art
In a so-called ink jet recording apparatus, ink is discharged from a recording head to thereby effect recording on a recording medium such as recording paper.
An ink storing device such as an ink tank for storing therein ink to be supplied to the recording head is mounted on a predetermined fixed region of the ink jet recording apparatus, or is carried on a carriage with the recording head. In the former case, an ink supply path such as an ink tube is provided between the recording head and the storing device, and this is designed to follow the movement of the carriage.
In the latter case, the ink supply path provided between the recording head and the storing device can be made relatively short. Therefore, the construction in which the ink storing device is carried on the carriage can be said to be a construction suitable for downsizing or simplifying the ink jet recording apparatus.
Among such constructions in which the recording head and the ink storing device (ink tank) are both carried on the carriage, there are a construction in which the recording head and the ink tank are formed integrally with each other and a construction in which the recording head and the ink tank are separably carried. In the construction wherein the recording head and the ink tank are formed integrally with each other, a cartridge comprising the ink tank and the recording head made integral with each other is interchanged with a new one at a point of time whereat the ink in the ink tank has become exhausted and therefore, this construction is easy to handle and thus has been spreading in recent years, but the expensive head is interchanged each time the ink becomes exhausted and this leads to the rise of running cost.
Also, in the construction wherein the recording head and the ink tank are separably carried, the ink tank alone can be interchanged when the ink becomes exhausted, and the head itself can also be interchanged at the end of its life. In ordinary use, generally it is impossible that the head becomes unusable due to its life before the ink in the ink tank is used up. Therefore, the ink tank alone is interchanged when the ink becomes exhausted and thus, running cost can be suppressed. However, it is necessary to make the connecting portion between the ink tank and the recording head elaborately so that the ink may not leak.
In any of the various ink jet recording apparatuses as described above, it is desirable to provide a construction for accurately knowing the amount of ink remaining in the ink storing means, in order to effect the interchange of the ink storing means at an appropriate time.
When the ink in the ink storing means becomes exhausted during recording, the discharge means of the recording head continues to create energy for discharge in the absence of the ink. Particularly, in an ink jet recording apparatus of the recently known thermal jet type in which heat energy is imparted to ink by heat energy generating means and the pressure by a change in the state of the ink is utilized to discharge the ink, a heater for discharge as the heat energy generating means is driven in the absence of the ink and therefore, not only the temperature of the recording head rises but also the recording head itself is damaged. Accordingly, the aforedescribed construction for knowing the remain state of ink can be said to be indispensable.
In recent years, there has come to be known a technique of making the volume of ink which can be contained in the ink storing means large to thereby reduce the frequency of interchange of the ink storing means. By such a technique, not only running cost can be reduced, but also the frequency of the manipulation cumbersome to the user can be decreased.
A technique of making the volume of ink in ink storing means large is proposed in U.S. Application Ser. No. 08/094,313. According to this application, use is made of an ink storing container in which a negative pressure generating member containing portion and an ink containing portion for containing ink are separated, whereby substantially all of ink except ink adhering to the wall surface in the ink containing portion can be used and the large volume of the ink contained in the ink storing container is achieved. Also, the leakage of the ink from a recording head can be prevented by the negative pressure generating member contained in the ink storing container and a stable ink supplying performance can be maintained for a long period.
Ink termination detecting devices for detecting the termination of ink in the ink storing container or the like of an ink jet recording apparatus include one using an optical element as disclosed in Japanese Laid-Open Patent Application No. 54-133373, one which detects by the conduction of an electrode member as disclosed in Japanese Patent Publication No. 1-17465, one which counts discharge pulse number as disclosed in Japanese Laid-Open Patent Application No. 59-194853, etc.
However, it has been difficult for the above-mentioned ink termination detecting devices (ink remain state detecting devices) according to the prior art to accurately detect the remain state of ink in the aforedescribed ink storing container wherein the negative pressure generating member containing portion and the ink containing portion are separated.
For example, among the above-mentioned devices according to the prior art, it has been difficult due to the structure of the ink storing container for one using an optical element and one which detects by the conduction of an electrode member to detect the exhaustion of the ink in the negative pressure generating member containing portion, and even if the remain state of the ink only in the ink containing portion is detected, ink may still remain in the negative pressure generating member containing portion, and this device could only be applied to the warning of the fact that the ink has decreased to some extent. Also, it has become difficult with the larger volume of ink for the device which counts discharge pulse number to detect the remain of ink accurately. Further, an attempt to effect the detection accurately has led to very high costs, and the amount of ink used differs depending on the irregularity of the initial amount of supply and the environment of use, and this has led to a problem that accurate detection cannot be accomplished.